1. Field of the Invention
The present invention relates to improved sharpening means for pocket and other knives. More particularly, the present invention provides an efficient, effective and easily used sharpening means which is integral to the structure of a knife.
2. General Background
Sharpening means for knives are known in various shapes, forms and materials, however most such means are separate devices from the knife itself and require some degree of expertise to be properly used. To overcome these drawbacks, knives with sharpening means incorporated into the knife or sheath have been developed and are known in the art. An additional problem associated with these type devices is that as the sharpening means becomes worn, there may not be enough surface area in contact with the blade edge to properly sharpen it. It is believed that the self-sharpening pocket knife of the present invention solves this problem.
Several devices have been patented which are aimed at incorporating a sharpening means into a knife or sheath.
U.S. Pat. No. 2,791,831, by Hollis, discloses a folding jackknife or pocket knife having abrasive strips lining opposite sides of the blade housing or chamber, so that the blade is sharpened when it is moved into contact with the strips when folding the blade for storage.
U.S. Pat. No. 2,416,929, by Kjorsvik, discloses a folding pocket knife with abrasive sharpening disks positioned inside the blade casing or housing so that the blade edge is sharpened when it is moved into contact with the disks when folding the blade for storage.
U.S. Pat. No. 4,501,068, by Palson, issued to The Phillips Manufacturing Company, of Canton, Mass., discloses a folding pocket knife having a cutting blade and sharpening blade, both sheathed within a chamber of the handle.
U.S. Pat. No. 1,170,433, by Ellebrecht, discloses a folding razor that is self-lubricating and comprises absorbent strips lining opposite sides of the blade housing so that the blade is lubricated when it is moved into contact with the strips when folded for storage.
U.S. Pat. No. 4,974,322, by Butka, discloses a knife with a blade or cutting member attached to a handle, with the blade being sharpened by inserting and rubbing it in its casing or sheath that is made of material more abrasive and stronger than the blade.
U.S. Pat. No. 1,208,435, by Young, discloses a folding knife with a sharpening whet stone mounted to the outer surface of the blade housing or frame.
U.S. Pat. Nos. 1,270,727 and 5,649,129 are also representative of the state of the art.
The above patents present in the art are directed to different devices for providing sharpening means as an integral part of a knife or sheath, but none of them address the problem of keeping the sharpening means in contact with the blade once the sharpening means becomes worn.
The preferred embodiment of the present invention solves the aforementioned problem in a straightforward and simple manner. What is provided is a self-sharpening pocket knife including a housing having abrasive stone strips or other sharpening means, and additional means for biasing the strips inward so that as the stone wears down there is always enough surface area in contact with the blade to sharpen it. The biasing means may take the form of foam rubber which expands, or multiple coiled springs, either means being positioned between the walls of the housing and the stone strips.
An additional embodiment of the present invention provides a housing or sheath for a straight knife incorporating the same sharpening and biasing means.
In view of the above, it is an object of the present invention to provide a self-sharpening pocket knife which maintains sufficient surface area with the blade to sharpen it as the sharpening means wears down.
It is an additional object of the present invention to provide a knife housing or sheath with integrated sharpening means that maintains sufficient surface area in contact with the blade to sharpen it as the sharpening means wears down.
The above objects of the present invention will become apparent from the drawing, the description given herein, and the appended claims.